Voyager: Through the door to eternity

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Dr Carolyn Porco is one of the world's leading planetary scientists and was part of the Voyager-1 imaging team. She helped Carl Sagan set up Voyager's famous "Pale Blue Dot" portrait of Earth when the probe had reached beyond Neptune in 1990. Here, she reflects on what it means to see the veteran craft finally make the leap to interstellar space.


It is a momentous occasion. We know now with certainty that the Voyager spacecraft, launched 36 years ago to spend the 1980s touring the outer solar system, has finally slipped beyond the protective magnetic bubble created by our Sun and into the nothingness of interstellar space.

Such an event happens for the first time in human history only once. And as reported in a publication today in the journal Science, it happened last summer.

Voyager was a mission of mythic proportions, with all the elements of Homeric legend, and I was unspeakably fortunate to have been a part of it.

I was young then, right out of graduate school, and somehow found myself a member of the imaging team and hitching a ride on the greatest journey of scientific exploration humanity had ever undertaken.

Written By: Carolyn Porco
continue to source article at bbc.co.uk

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  1. The media is focussed on “leaving the Solar System”, which basically fails to recognise the interactions of matter within the galaxy.

    The Solar atmosphere between the planets is extremely thin (referred to as a vacuum) and the inter-stellar traces of gas are even thinner. What Voyager 1 has been measuring is the transition at the heliopause.

    We do not know where the “edge of the Solar System” is.

    There could be planetoids or planets orbiting the Sun in the Oort Cloud as far out as well on the way to the Proxima or Alpha Centauri.

    The scale on this first link has been compacted so as to fit the screen.

    oort-cloud orbit -images

    • In reply to #2 by Alan4discussion:

      Hi Alan,

      We do not know where the “edge of the Solar System” is.

      It seems to me that this is not a question about ‘knowing’ – it’s a question about definitions.

      NASA may be guilty of applying a definition that other people don’t recognise (including some space scientists) when they say:

      The data that finally convinced the mission team to call the jump to interstellar space came from the probe’s Plasma Wave Science (PWS) instrument. This can measure the density of charged particles in Voyager’s vicinity.

      Scientists have long theorised such a spike would eventually be observed if Voyager could get beyond the influence of the magnetic fields and particle wind that billow from the surface of the Sun.

      The full original definition story is here at the BBC.

      No-one else has built spacecraft, and spent more than 35 years monitoring and nursing them across 12 billion miles of space, so it seems to me that NASA – however we might define a Solar System – has won bragging rights.

      Be happy.

      Peace.

  2. In reply to #3 by Stephen of Wimbledon:

    We do not know where the “edge of the Solar System” is.

    It seems to me that this is not a question about ‘knowing’ – it’s a question about definitions.

    NASA may be guilty of applying a definition that other people don’t recognise (including some space…

    I don’t think the space scientists at NASA would make this sort of mistake over definitions.

    Voyager probe ‘leaves Solar System’ – By Jonathan Amos

    The wrong title is from BBC correspondent Jonathan Amos.

    He confuses the Solar atmosphere with the Solar System. It is like claiming you have left Earth orbit by crossing the stratosphere!

    Unfortunately, I see that my links which explain this – which I tested shortly after posting them – no longer work.
    Edit:- After posting the new link below the old ones now seem to work again! – Some Google quirk perhaps!

    https://www.google.co.uk/search?q=oort-cloud+orbit&tbm=isch&tbo=u&source=univ&sa=X&ei=6QozUsCzBMXX0QX9toDQAw&ved=0CEkQsAQ&biw=955&bih=441&dpr=1

    Any way there are orbiting bodies of the Solar System further out than Voyager’s present position.

    • In reply to #4 by Alan4discussion:

      Hi Alan,

      I ‘liked’ your comment, because this is an interesting conversation.

      On the other hand, we seem to be talking at cross-purposes – surely, that never happens on the Net?

      I don’t think the space scientists at NASA would make this sort of mistake over definitions.

      No-one is claiming (as far as I know – though I haven’t read any Roscosmos comments yet, call me cynical) that anyone is making a mistake.

      I was merely suggesting that NASA have chosen a convenient definition, while I simultaneously acknowledged their right to do so.

      The wrong title is from BBC correspondent Jonathan Amos.

      Mr. Amos may not be aware of this side-bar so I’ll defend him. Amos is only repeating what he read. Follow the breadcrumbs: Amos’ page at my original link also has a link to the on-line version of Science. Science is the publication of the American Association for the Advancement of Science (AAAS) where there is a paper on this event. The Paper in question lists three primary authors including one L. F. Burlaga of NASA/Goddard Space Flight Center. The on-line AAAS paper’s page also links to an AAAS news item entitled It’s Official—Voyager Has Left the Solar System which further quotes former NASA staff. Other NASA staff can be seen quoted as saying similar things in other media outlets.

      I’m not saying that Amos is right, only that he was justified in using the terminology that he did.

      [Amos] confuses the Solar atmosphere with the Solar System. It is like claiming you have left Earth orbit by crossing the stratosphere!

      I agree – providing we don’t accept NASA’s definition of where the solar system has an ‘edge’ – and what that boundary, in turn, describes – then Voyager 1 has not left our Solar System. It’s all about definitions – as I think I may have mentioned.

      Unfortunately, I see that my links which explain this – which I tested shortly after posting them – no longer work.

      No worries, I get it. The Kuiper Belt or the Oort Cloud could be a better method of defining where the influence of our Sun ends.

      My point was that complaining about NASA’s definition tends to diminish a great achievement. That just seems to me to be a little ignoble and ungenerous. Who else is exploring 12 billion miles out.

      By-the-by, I just stumbled across this very interesting article on the size of the Solar System. One definition there has the size at 2 light years – which puts our discussion in yet another perspective (one astronomical unit is a bit more than 8 light-minutes in distance terms). On that basis, Voyager 1 has barely crossed to the edge of the yolk inside an egg – in a star system as big as a mega-sized chicken farm. Note to any pedants: I didn’t calculate this I’m using an artistic definition.

      So basically Alan, that’s where I was coming from in a nutshell … or Chestnut Tree … or Wood … etc. etc..

      Peace.

      • In reply to #8 by Stephen of Wimbledon:

        Hi Stephen

        It is unfortunate that my very first link does not work. It was to the image which showed the Solar System and the scale calibrated in powers of 10 out to the Centauri System. Here is another article which has another copy of that graphic: http://www.gizmag.com/voyager-leaves-solar-system/29058/ – This one is calibrated in AU (Astronomical Units). It also clearly shows the Oort cloud well outside the Termination Shock and the Heliopause.

        By-the-by, I just stumbled across this very interesting article on the size of the Solar System. One definition there has the size at 2 light years – which puts our discussion in yet another perspective (one astronomical unit is a bit more than 8 light-minutes in distance terms).
        On that basis, Voyager 1 has barely crossed to the edge of the yolk inside an egg – in a star system as big as a mega-sized chicken farm.

        Perhaps I am being a bit pedantic, but I do expect science correspondents and people cited as space scientists, to actually know the locations of the orbits in the Solar System, when commenting on the Solar System!
        It just seems silly to me to confuse the public with claims about “leaving the Solar System”, when thousands of its planetiods are orbiting a hundred times further out from the Sun than the Heliopause!
        Voyager is leaving the Heliosphere!

        These issues are important in the future of robotic or manned interstellar travel. These cometary and other bodies could be used as stepping-stones or resources for refuelling craft.

        .. . . . .. . . . . this very interesting article on the size of the Solar System. One definition there has the size at 2 light years
        Note to any pedants: I didn’t calculate this I’m using an artistic definition.

        You are about correct. It is reasonable to consider about half way to Centauri as the transition from one star system to the next.

        • In reply to #9 by Alan4discussion:

          Hi Alan,

          Many thanks for that last link in your Comment 9. That’s an excellent article and video – it really explains it.

          This sort of thing makes me feel so lucky to be alive now, in the 21st Century. We are in a position to look backwards – through history, anthropology and biology – to our beginnings, and to look forwards to the challenges of the vast Universe and the promise of so much to come.

          How is it that hardly any major religion has looked at science and concluded, ‘This is better than we thought! The Universe is much bigger than our prophets said, grander, more subtle, more elegant’?

          Carl Sagan

          Cheers.

          • In reply to #11 by Stephen of Wimbledon:

            In reply to #9 by Alan4discussion:

            Hi Alan,

            Many thanks for that last link in your Comment 9. That’s an excellent article and video – it really explains it.

            I think it spells out the issues much better than many other news articles.

            So to clarify for other readers From the link @9

            So, has Voyager 1 finally left the Solar System? The quick answer is, yes and no. Yes, it is in interstellar space where the solar winds and magnetic field no longer holds sway, but there is still gravity to contend with. The very outer frontier where the Sun’s gravity is finally eclipsed by the collective gravitational pull of the rest of the Galaxy is the Oort cloud (and technically it’s outer edge), where the comets that periodically visit the inner Solar System originate and where the pull of the Sun or passing stars sometimes disturb them and send them arcing towards us.

            Astronomers have regarded the outer edge of the Solar System as being between 1,000 and 100,000 AU distant (1 AU = 149,597,870,700 mi) since the 1960s, but it is a bit like claiming that the edge of Japan is Scotland because you can detect Japanese earthquakes from there. Nevertheless, there is one good reason to make August 25, 2012 the official day. Voyager is only 125 AU from Earth and [will not] reach the Oort cloud for 300 years and won’t pass through it for another 30,000 years, so the champagne would be bit off by then.

            All credit to the team that put the Voyager project together, and I wish them well with their celebration.

            I only hope that when we want to send a probe to the edge of the Solar-System (Ooort Cloud and beyond) the public will not consider it a waste of time as something which they have been told has already been done!

            Project Icarus Pathfinder (1,000 AU) and Starfinder (10,000 AU) Concepts – (Project Daedalus)

            If you are looking for lots of realistic or speculative ideas, past and present, this rather slow-loading link could provide some interesting subjects.

            http://ukseds.org/conference2013/docs/UKSEDS%28kflong%29Lecture-I4IS.pdf

            The Emergence of “Interstellar Studies”

      • In reply to #8 by Stephen of Wimbledon:

        I think we have cleared up the uncertainties, but just to clarify the definitions.

        I was merely suggesting that NASA have chosen a convenient definition,

        NASA has chosen to claim that the heliopause is the edge of the “Solar System”. – The only basis I can see for this is media hype!

        The normal definition of a planetary system is the planet and its orbiting moons, rings etc.

        The normal astronomical definition of a solar system, is its star and the orbiting planets and planetoids (or accretion disk etc) circulating in its gravity well.

        I can’t see any scientific basis for deviating from these definitions: – Certainly not in a system of orbits around a single star, as is the case with out Sun. Binary star systems can get more complicated, but again, they would be regarded as consisting of the stars and the orbiting planetary material, grouped in orbits by gravity.

        Various people seem to have been carried away from their science by media hype and celebrations. These celebrations in my view, are diminished , rather than enhanced, by silly unscientific claims, and will be viewed with hindsight as foolish delusions.

        Claiming successfully reaching landmarks 30,000 years early, does make people look rather foolish!

        There is every chance if developments continue, that the Voyagers will be overtaken by later probes before they reach the outer edge of the Oort Cloud – and probably before they reach the inner edge!

        Project Icarus (Interstellar Probe Design Study) – From Wikipedia,

        http://www.icarusinterstellar.org/dr-rob-adams-talks-with-hailey-bright-about-fusion-propulsion/

  3. I like the sound of humans being an “interstellar species” now. From The Guardian, a comment:

    The Voyager satellite passes the boundary of the Solar System. We live in a time that the human race has become an interstellar species. A quite remarkable achievement; from the Wright brothers to interstellar in 110 years. In the grand scheme of things, this might not appear as far-reaching as the first flight, or as dramatic and unifying as the first step on the Moon, but I think in the future, looking back, this period will take on special significance. When one considers thousands of years of human hisotry and civilisation, but then the relative speed with which we have gone from flight to space, it becomes quite startling how quickly our technological advancement is progressing. It is terrifying to consider where we will be even in the next fifty years. Terrifying, but also incredibly exciting. Personally, I think this story should get more coverage as it is quite a moment in the history of the human race. (silentstar 101)

    Mike

  4. I overheard a couple of pensioners on the bus on my way to work talking about this. One said, ‘Bloody typical, first we pollute the land with our rubbish, then the seas, the atmosphere and low orbit. Now we’ve not only dumped stuff in the solar system but deep space too. What will our neighbours think?’
    A bit harsh calling voyager junk, and as Alan would be quick to point out, it’s not deep space yet. I’d have corrected them if it had actually happened.

    • In reply to #7 by headswapboy:

      I overheard a couple of pensioners on the bus on my way to work talking about this. One said, ‘Bloody typical, first we pollute the land with our rubbish, then the seas, the atmosphere and low orbit. Now we’ve not only dumped stuff in the solar system but deep space too. What will our neighbours thi…

      Blime, if “our neighbours” show any concern about how much of a mess we’ve made of interstellar space I’d be both amazed they could even spot something so small in such an unimaginably large volume of space while deeply unimpressed by their unatainable standards of cleanliness.

      i’m not exactly sure of the relative size of a space probe and the heliosphere but i’m guessing it’s not overly cluttered

  5. NASA has, over the years, done great work in astronomy and space exploration. It saddens me, therefore, to see its name being tarnished, albeit slightly, by the use of such expressions as the “edge” of the solar system, and the “door” through which Voyager leapt into interstellar space.

    The solar system has no more an edge than gravity or magnetism, which extend in all directions into oblivion. What we can say, for the sake of accuracy, is that Voyager is moving away from the gravitational influence of one stellar object and will eventually be closer to the gravitational influence of another, with no edges and doors in between.

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